//包含std::shared_ptr<>实例的线程安全队列
template <typename T>
class threadsafe_queue
{
private:
	mutable std::mutex mut;
	std::queue<std::shared_ptr<T> > data_queue;
	std::condition_variable data_cond;
public:
	threadsafe_queue();
	{}

	void wait_and_pop(T& value)
	{
		std::unique_lock<std::mutex> lk(mut);
		data_cond.wait(lk,[this]{return !data_queue.empty();});
		value=std::move(*data_queue.front());
		data_queue.pop();
	}

	bool try_pop(T& value)
	{
		std::lock_guard<std::mutex> lk(mut);
		if(data_queue.empty())
			return false;
		value=std::move(*data_queue.front());
		data_queue.pop();
		return true;
	}

	std::shared_ptr<T> wait_and_pop()
	{
		std::unique_lock<std::mutex> lk(mut);
		data_cond.wait(lk,[this]{return !data_queue.empty();});
		std::shared_ptr<T> res=data_queue.front();
		data_queue.pop();
		return res;
	}

	std::shared_ptr<T> try_pop()
	{
		std::lock_guard<std::mutex> lk(mut);
		if(data_queue.empty())
			return std::shared_ptr<T>();
		std::shared_ptr<T> res=data_queue.front();
		data_queue.pop();
		return res;
	}

	void push(T new_value)
	{
		std::shared_ptr<T> data(std::make_shared<T>(std::move(new_value)));
		std::lock_guard<std::mutex> lk(mut);
		data_queue.push(data);
		data_cond.notify_one();
	}

	bool empty() const
	{
		std::lock_guard<std::mutex> lk(mut);
		return data_queue.empty();
	}
};